Many small internal combustion engines, for example those associated with outdoor power equipment such as, for example, a chain saw, are started by a rope pull starter. While the rope is being pulled, it is not uncommon for the user at the same time to maintain the throttle in a partially or completely open condition in order to aid engine start-up by providing the engine with an increased flow of an air/fuel mixture. Any engine driven equipment, however, is potentially dangerous if used negligently or carelessly, and therefore it is desirable that one hand be free to hold or stabilize the equipment during start-up.
In those kinds of equipment where one hand is needed to maintain the throttle in a partially open or fully open position, however, it is difficult, and in some kinds of equipment, impossible, to effectively hold the apparatus in a stable position during start-up. To relieve this problem, the throttle has been provided with a throttle lock on the handle of the apparatus to maintain the throttle plate in a desired starting position. These locks however require an adjustment device to allow for the buildup of tolerances from the throttle trigger through the wire linkage and the holes of the bellcrank in the carburetor. Thus, these devices are necessarily more expensive and sometimes less reliable than may otherwise be desired.
It is therefore an object of this invention to provide a carburetor throttle lock which is very reliable, low in cost, and which does not require continuous adjustment because of the buildup of tolerances in the lock to carburetor linkage. Other objects of the invention are to provide an apparatus which may be attached to the carburetor itself, which is automatically released when the throttle trigger is used and which does not require user adjustment.
A further object of the invention is to provide a throttle lock for an internal combustion engine operated apparatus which provides a user with a safe and stable engine start-up procedure.
It is another object of the invention to provide a throttle lock which cannot be accidentally engaged while operating the engine.